1. Field of the Invention
The present invention relates to a wheel set guidance assembly for suspending a wheel set bearing of a wheel set to a bogie frame. The invention further relates to a bogie, in particularly to a train bogie, comprising such a wheel set guidance assembly and a method for providing a bogie with optimal wheel set guidance.
2. Description of the Related Art
DE 41 41 463 describes a wheel set guidance assembly for a train bogie in which a coil spring is arranged on top of the wheel set bearing for carrying the bogie frame and in which the wheel set bearing is further attached to the bogie frame by a rigid steering arm longitudinally extending from the wheel set bearing to a console rigidly mounted on the bogie frame. Metal-rubber elements are arranged between the steering arm and the bogie frame guidance console. For the purposes of this specification, the longitudinal, lateral and vertical directions are references to the respective directions relative to the bogie.
DE 43 15 568 describes a wheel set guidance assembly consisting of two coil springs for the vertical suspension and guidance and rubber elements engaging a guidance pin to take over both longitudinal and lateral guidance of the wheel-set.
One problem of the known wheel set guidance assemblies is that they are not easily adaptable to specific rail networks and that an optimum guidance of the wheel set often cannot be achieved. This problem occurs in particular in bogies that have to rum in different networks with a specific portion of highly demanding tracks having, for example, narrow curves. A guidance assembly that is not optimised can cause undesirable wear of the wheels, noise, passenger discomfort because of undesired movements of the car body, and more importantly a risk of derailment.
A further problem of the prior art wheel guidance assemblies is that the rail tracking forces that occur during driving, in particular on curved tracks, are for a large part carried by the longitudinal beams of the bogie frame. These beams keep the wheel set guidance elements, spring, dampers and other components in position. The stiffness of the bogie frame must be designed to accommodate such forces. Prior art bogie frames, designed for use in a variety of situations, are typically over-designed to meet all stiffness requirements and are hence undesirably heavy.
Accordingly, there is a particular need for an improved wheel set guidance assembly. Preferably, such an improved assembly would be compact, to allow for a low bogie construction and a low car body floor,